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Date: Wed, 27 Apr 2011 20:10:47 +0200
From: Tomas Hoger <>
To:, "Steven M. Christey" <>
Cc:, Ludwig Nussel <>,
        Petr Baudis <>
Subject: Re: Suid mount helpers fail to anticipate

On Wed, 27 Apr 2011 11:00:16 -0400 Dan Rosenberg wrote:

> >> util-linux mount
> >> =============
> >> * Edits /etc/mtab.tmp with custom my_addmntent(), behaves
> >> identically to glibc addmntent() in terms of return code
> >> * Succeeds on partial writes, does not remove temp file on failure
> >> (could result in additional corruption of /etc/mtab through
> >> multiple invocations), does not remove lock file /etc/mtab~ on
> >> failure (also an issue)
> >
> > Dan, would you mind clarifying the way to achieve mtab corruption
> > via truncated left-over mtab.tmp file and multiple invocations?
> >  After some discussion with our util-linux maintainer, we fail to
> > see an obvious way.  util-linux opens mtab.tmp using "w" fopen
> > open, i.e. using O_TRUNC open flag.  So if there's any mtab.tmp
> > file found, it's overwritten and its existence does not block
> > further use of mount / umount as existence of mtab~ lock file does.
> Ah, quite right.  I missed that since I was just doing a quick survey
> of a bunch of helpers.  It seems the mtab.tmp file isn't an issue.
> Thanks for looking into it.

Ok, thank you!

Steve, it seems CVE-2011-1676 should get marked as rejected or disputed.


Tomas Hoger / Red Hat Security Response Team

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